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1  // SPDX-License-Identifier: GPL-2.0-or-later
2  /* audit.c -- Auditing support
3   * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
4   * System-call specific features have moved to auditsc.c
5   *
6   * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
7   * All Rights Reserved.
8   *
9   * Written by Rickard E. (Rik) Faith <faith@redhat.com>
10   *
11   * Goals: 1) Integrate fully with Security Modules.
12   *	  2) Minimal run-time overhead:
13   *	     a) Minimal when syscall auditing is disabled (audit_enable=0).
14   *	     b) Small when syscall auditing is enabled and no audit record
15   *		is generated (defer as much work as possible to record
16   *		generation time):
17   *		i) context is allocated,
18   *		ii) names from getname are stored without a copy, and
19   *		iii) inode information stored from path_lookup.
20   *	  3) Ability to disable syscall auditing at boot time (audit=0).
21   *	  4) Usable by other parts of the kernel (if audit_log* is called,
22   *	     then a syscall record will be generated automatically for the
23   *	     current syscall).
24   *	  5) Netlink interface to user-space.
25   *	  6) Support low-overhead kernel-based filtering to minimize the
26   *	     information that must be passed to user-space.
27   *
28   * Audit userspace, documentation, tests, and bug/issue trackers:
29   * 	https://github.com/linux-audit
30   */
31  
32  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
33  
34  #include <linux/file.h>
35  #include <linux/init.h>
36  #include <linux/types.h>
37  #include <linux/atomic.h>
38  #include <linux/mm.h>
39  #include <linux/export.h>
40  #include <linux/slab.h>
41  #include <linux/err.h>
42  #include <linux/kthread.h>
43  #include <linux/kernel.h>
44  #include <linux/syscalls.h>
45  #include <linux/spinlock.h>
46  #include <linux/rcupdate.h>
47  #include <linux/mutex.h>
48  #include <linux/gfp.h>
49  #include <linux/pid.h>
50  
51  #include <linux/audit.h>
52  
53  #include <net/sock.h>
54  #include <net/netlink.h>
55  #include <linux/skbuff.h>
56  #ifdef CONFIG_SECURITY
57  #include <linux/security.h>
58  #endif
59  #include <linux/freezer.h>
60  #include <linux/pid_namespace.h>
61  #include <net/netns/generic.h>
62  
63  #include "audit.h"
64  
65  /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
66   * (Initialization happens after skb_init is called.) */
67  #define AUDIT_DISABLED		-1
68  #define AUDIT_UNINITIALIZED	0
69  #define AUDIT_INITIALIZED	1
70  static int	audit_initialized;
71  
72  u32		audit_enabled = AUDIT_OFF;
73  bool		audit_ever_enabled = !!AUDIT_OFF;
74  
75  EXPORT_SYMBOL_GPL(audit_enabled);
76  
77  /* Default state when kernel boots without any parameters. */
78  static u32	audit_default = AUDIT_OFF;
79  
80  /* If auditing cannot proceed, audit_failure selects what happens. */
81  static u32	audit_failure = AUDIT_FAIL_PRINTK;
82  
83  /* private audit network namespace index */
84  static unsigned int audit_net_id;
85  
86  /**
87   * struct audit_net - audit private network namespace data
88   * @sk: communication socket
89   */
90  struct audit_net {
91  	struct sock *sk;
92  };
93  
94  /**
95   * struct auditd_connection - kernel/auditd connection state
96   * @pid: auditd PID
97   * @portid: netlink portid
98   * @net: the associated network namespace
99   * @rcu: RCU head
100   *
101   * Description:
102   * This struct is RCU protected; you must either hold the RCU lock for reading
103   * or the associated spinlock for writing.
104   */
105  struct auditd_connection {
106  	struct pid *pid;
107  	u32 portid;
108  	struct net *net;
109  	struct rcu_head rcu;
110  };
111  static struct auditd_connection __rcu *auditd_conn;
112  static DEFINE_SPINLOCK(auditd_conn_lock);
113  
114  /* If audit_rate_limit is non-zero, limit the rate of sending audit records
115   * to that number per second.  This prevents DoS attacks, but results in
116   * audit records being dropped. */
117  static u32	audit_rate_limit;
118  
119  /* Number of outstanding audit_buffers allowed.
120   * When set to zero, this means unlimited. */
121  static u32	audit_backlog_limit = 64;
122  #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
123  static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
124  
125  /* The identity of the user shutting down the audit system. */
126  static kuid_t		audit_sig_uid = INVALID_UID;
127  static pid_t		audit_sig_pid = -1;
128  static u32		audit_sig_sid;
129  
130  /* Records can be lost in several ways:
131     0) [suppressed in audit_alloc]
132     1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
133     2) out of memory in audit_log_move [alloc_skb]
134     3) suppressed due to audit_rate_limit
135     4) suppressed due to audit_backlog_limit
136  */
137  static atomic_t	audit_lost = ATOMIC_INIT(0);
138  
139  /* Monotonically increasing sum of time the kernel has spent
140   * waiting while the backlog limit is exceeded.
141   */
142  static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0);
143  
144  /* Hash for inode-based rules */
145  struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
146  
147  static struct kmem_cache *audit_buffer_cache;
148  
149  /* queue msgs to send via kauditd_task */
150  static struct sk_buff_head audit_queue;
151  /* queue msgs due to temporary unicast send problems */
152  static struct sk_buff_head audit_retry_queue;
153  /* queue msgs waiting for new auditd connection */
154  static struct sk_buff_head audit_hold_queue;
155  
156  /* queue servicing thread */
157  static struct task_struct *kauditd_task;
158  static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
159  
160  /* waitqueue for callers who are blocked on the audit backlog */
161  static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
162  
163  static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
164  				   .mask = -1,
165  				   .features = 0,
166  				   .lock = 0,};
167  
168  static char *audit_feature_names[2] = {
169  	"only_unset_loginuid",
170  	"loginuid_immutable",
171  };
172  
173  /**
174   * struct audit_ctl_mutex - serialize requests from userspace
175   * @lock: the mutex used for locking
176   * @owner: the task which owns the lock
177   *
178   * Description:
179   * This is the lock struct used to ensure we only process userspace requests
180   * in an orderly fashion.  We can't simply use a mutex/lock here because we
181   * need to track lock ownership so we don't end up blocking the lock owner in
182   * audit_log_start() or similar.
183   */
184  static struct audit_ctl_mutex {
185  	struct mutex lock;
186  	void *owner;
187  } audit_cmd_mutex;
188  
189  /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
190   * audit records.  Since printk uses a 1024 byte buffer, this buffer
191   * should be at least that large. */
192  #define AUDIT_BUFSIZ 1024
193  
194  /* The audit_buffer is used when formatting an audit record.  The caller
195   * locks briefly to get the record off the freelist or to allocate the
196   * buffer, and locks briefly to send the buffer to the netlink layer or
197   * to place it on a transmit queue.  Multiple audit_buffers can be in
198   * use simultaneously. */
199  struct audit_buffer {
200  	struct sk_buff       *skb;	/* formatted skb ready to send */
201  	struct audit_context *ctx;	/* NULL or associated context */
202  	gfp_t		     gfp_mask;
203  };
204  
205  struct audit_reply {
206  	__u32 portid;
207  	struct net *net;
208  	struct sk_buff *skb;
209  };
210  
211  /**
212   * auditd_test_task - Check to see if a given task is an audit daemon
213   * @task: the task to check
214   *
215   * Description:
216   * Return 1 if the task is a registered audit daemon, 0 otherwise.
217   */
auditd_test_task(struct task_struct * task)218  int auditd_test_task(struct task_struct *task)
219  {
220  	int rc;
221  	struct auditd_connection *ac;
222  
223  	rcu_read_lock();
224  	ac = rcu_dereference(auditd_conn);
225  	rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
226  	rcu_read_unlock();
227  
228  	return rc;
229  }
230  
231  /**
232   * audit_ctl_lock - Take the audit control lock
233   */
audit_ctl_lock(void)234  void audit_ctl_lock(void)
235  {
236  	mutex_lock(&audit_cmd_mutex.lock);
237  	audit_cmd_mutex.owner = current;
238  }
239  
240  /**
241   * audit_ctl_unlock - Drop the audit control lock
242   */
audit_ctl_unlock(void)243  void audit_ctl_unlock(void)
244  {
245  	audit_cmd_mutex.owner = NULL;
246  	mutex_unlock(&audit_cmd_mutex.lock);
247  }
248  
249  /**
250   * audit_ctl_owner_current - Test to see if the current task owns the lock
251   *
252   * Description:
253   * Return true if the current task owns the audit control lock, false if it
254   * doesn't own the lock.
255   */
audit_ctl_owner_current(void)256  static bool audit_ctl_owner_current(void)
257  {
258  	return (current == audit_cmd_mutex.owner);
259  }
260  
261  /**
262   * auditd_pid_vnr - Return the auditd PID relative to the namespace
263   *
264   * Description:
265   * Returns the PID in relation to the namespace, 0 on failure.
266   */
auditd_pid_vnr(void)267  static pid_t auditd_pid_vnr(void)
268  {
269  	pid_t pid;
270  	const struct auditd_connection *ac;
271  
272  	rcu_read_lock();
273  	ac = rcu_dereference(auditd_conn);
274  	if (!ac || !ac->pid)
275  		pid = 0;
276  	else
277  		pid = pid_vnr(ac->pid);
278  	rcu_read_unlock();
279  
280  	return pid;
281  }
282  
283  /**
284   * audit_get_sk - Return the audit socket for the given network namespace
285   * @net: the destination network namespace
286   *
287   * Description:
288   * Returns the sock pointer if valid, NULL otherwise.  The caller must ensure
289   * that a reference is held for the network namespace while the sock is in use.
290   */
audit_get_sk(const struct net * net)291  static struct sock *audit_get_sk(const struct net *net)
292  {
293  	struct audit_net *aunet;
294  
295  	if (!net)
296  		return NULL;
297  
298  	aunet = net_generic(net, audit_net_id);
299  	return aunet->sk;
300  }
301  
audit_panic(const char * message)302  void audit_panic(const char *message)
303  {
304  	switch (audit_failure) {
305  	case AUDIT_FAIL_SILENT:
306  		break;
307  	case AUDIT_FAIL_PRINTK:
308  		if (printk_ratelimit())
309  			pr_err("%s\n", message);
310  		break;
311  	case AUDIT_FAIL_PANIC:
312  		panic("audit: %s\n", message);
313  		break;
314  	}
315  }
316  
audit_rate_check(void)317  static inline int audit_rate_check(void)
318  {
319  	static unsigned long	last_check = 0;
320  	static int		messages   = 0;
321  	static DEFINE_SPINLOCK(lock);
322  	unsigned long		flags;
323  	unsigned long		now;
324  	unsigned long		elapsed;
325  	int			retval	   = 0;
326  
327  	if (!audit_rate_limit) return 1;
328  
329  	spin_lock_irqsave(&lock, flags);
330  	if (++messages < audit_rate_limit) {
331  		retval = 1;
332  	} else {
333  		now     = jiffies;
334  		elapsed = now - last_check;
335  		if (elapsed > HZ) {
336  			last_check = now;
337  			messages   = 0;
338  			retval     = 1;
339  		}
340  	}
341  	spin_unlock_irqrestore(&lock, flags);
342  
343  	return retval;
344  }
345  
346  /**
347   * audit_log_lost - conditionally log lost audit message event
348   * @message: the message stating reason for lost audit message
349   *
350   * Emit at least 1 message per second, even if audit_rate_check is
351   * throttling.
352   * Always increment the lost messages counter.
353  */
audit_log_lost(const char * message)354  void audit_log_lost(const char *message)
355  {
356  	static unsigned long	last_msg = 0;
357  	static DEFINE_SPINLOCK(lock);
358  	unsigned long		flags;
359  	unsigned long		now;
360  	int			print;
361  
362  	atomic_inc(&audit_lost);
363  
364  	print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
365  
366  	if (!print) {
367  		spin_lock_irqsave(&lock, flags);
368  		now = jiffies;
369  		if (now - last_msg > HZ) {
370  			print = 1;
371  			last_msg = now;
372  		}
373  		spin_unlock_irqrestore(&lock, flags);
374  	}
375  
376  	if (print) {
377  		if (printk_ratelimit())
378  			pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
379  				atomic_read(&audit_lost),
380  				audit_rate_limit,
381  				audit_backlog_limit);
382  		audit_panic(message);
383  	}
384  }
385  
audit_log_config_change(char * function_name,u32 new,u32 old,int allow_changes)386  static int audit_log_config_change(char *function_name, u32 new, u32 old,
387  				   int allow_changes)
388  {
389  	struct audit_buffer *ab;
390  	int rc = 0;
391  
392  	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
393  	if (unlikely(!ab))
394  		return rc;
395  	audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old);
396  	audit_log_session_info(ab);
397  	rc = audit_log_task_context(ab);
398  	if (rc)
399  		allow_changes = 0; /* Something weird, deny request */
400  	audit_log_format(ab, " res=%d", allow_changes);
401  	audit_log_end(ab);
402  	return rc;
403  }
404  
audit_do_config_change(char * function_name,u32 * to_change,u32 new)405  static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
406  {
407  	int allow_changes, rc = 0;
408  	u32 old = *to_change;
409  
410  	/* check if we are locked */
411  	if (audit_enabled == AUDIT_LOCKED)
412  		allow_changes = 0;
413  	else
414  		allow_changes = 1;
415  
416  	if (audit_enabled != AUDIT_OFF) {
417  		rc = audit_log_config_change(function_name, new, old, allow_changes);
418  		if (rc)
419  			allow_changes = 0;
420  	}
421  
422  	/* If we are allowed, make the change */
423  	if (allow_changes == 1)
424  		*to_change = new;
425  	/* Not allowed, update reason */
426  	else if (rc == 0)
427  		rc = -EPERM;
428  	return rc;
429  }
430  
audit_set_rate_limit(u32 limit)431  static int audit_set_rate_limit(u32 limit)
432  {
433  	return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
434  }
435  
audit_set_backlog_limit(u32 limit)436  static int audit_set_backlog_limit(u32 limit)
437  {
438  	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
439  }
440  
audit_set_backlog_wait_time(u32 timeout)441  static int audit_set_backlog_wait_time(u32 timeout)
442  {
443  	return audit_do_config_change("audit_backlog_wait_time",
444  				      &audit_backlog_wait_time, timeout);
445  }
446  
audit_set_enabled(u32 state)447  static int audit_set_enabled(u32 state)
448  {
449  	int rc;
450  	if (state > AUDIT_LOCKED)
451  		return -EINVAL;
452  
453  	rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
454  	if (!rc)
455  		audit_ever_enabled |= !!state;
456  
457  	return rc;
458  }
459  
audit_set_failure(u32 state)460  static int audit_set_failure(u32 state)
461  {
462  	if (state != AUDIT_FAIL_SILENT
463  	    && state != AUDIT_FAIL_PRINTK
464  	    && state != AUDIT_FAIL_PANIC)
465  		return -EINVAL;
466  
467  	return audit_do_config_change("audit_failure", &audit_failure, state);
468  }
469  
470  /**
471   * auditd_conn_free - RCU helper to release an auditd connection struct
472   * @rcu: RCU head
473   *
474   * Description:
475   * Drop any references inside the auditd connection tracking struct and free
476   * the memory.
477   */
auditd_conn_free(struct rcu_head * rcu)478  static void auditd_conn_free(struct rcu_head *rcu)
479  {
480  	struct auditd_connection *ac;
481  
482  	ac = container_of(rcu, struct auditd_connection, rcu);
483  	put_pid(ac->pid);
484  	put_net(ac->net);
485  	kfree(ac);
486  }
487  
488  /**
489   * auditd_set - Set/Reset the auditd connection state
490   * @pid: auditd PID
491   * @portid: auditd netlink portid
492   * @net: auditd network namespace pointer
493   *
494   * Description:
495   * This function will obtain and drop network namespace references as
496   * necessary.  Returns zero on success, negative values on failure.
497   */
auditd_set(struct pid * pid,u32 portid,struct net * net)498  static int auditd_set(struct pid *pid, u32 portid, struct net *net)
499  {
500  	unsigned long flags;
501  	struct auditd_connection *ac_old, *ac_new;
502  
503  	if (!pid || !net)
504  		return -EINVAL;
505  
506  	ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
507  	if (!ac_new)
508  		return -ENOMEM;
509  	ac_new->pid = get_pid(pid);
510  	ac_new->portid = portid;
511  	ac_new->net = get_net(net);
512  
513  	spin_lock_irqsave(&auditd_conn_lock, flags);
514  	ac_old = rcu_dereference_protected(auditd_conn,
515  					   lockdep_is_held(&auditd_conn_lock));
516  	rcu_assign_pointer(auditd_conn, ac_new);
517  	spin_unlock_irqrestore(&auditd_conn_lock, flags);
518  
519  	if (ac_old)
520  		call_rcu(&ac_old->rcu, auditd_conn_free);
521  
522  	return 0;
523  }
524  
525  /**
526   * kauditd_print_skb - Print the audit record to the ring buffer
527   * @skb: audit record
528   *
529   * Whatever the reason, this packet may not make it to the auditd connection
530   * so write it via printk so the information isn't completely lost.
531   */
kauditd_printk_skb(struct sk_buff * skb)532  static void kauditd_printk_skb(struct sk_buff *skb)
533  {
534  	struct nlmsghdr *nlh = nlmsg_hdr(skb);
535  	char *data = nlmsg_data(nlh);
536  
537  	if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
538  		pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
539  }
540  
541  /**
542   * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
543   * @skb: audit record
544   *
545   * Description:
546   * This should only be used by the kauditd_thread when it fails to flush the
547   * hold queue.
548   */
kauditd_rehold_skb(struct sk_buff * skb)549  static void kauditd_rehold_skb(struct sk_buff *skb)
550  {
551  	/* put the record back in the queue at the same place */
552  	skb_queue_head(&audit_hold_queue, skb);
553  }
554  
555  /**
556   * kauditd_hold_skb - Queue an audit record, waiting for auditd
557   * @skb: audit record
558   *
559   * Description:
560   * Queue the audit record, waiting for an instance of auditd.  When this
561   * function is called we haven't given up yet on sending the record, but things
562   * are not looking good.  The first thing we want to do is try to write the
563   * record via printk and then see if we want to try and hold on to the record
564   * and queue it, if we have room.  If we want to hold on to the record, but we
565   * don't have room, record a record lost message.
566   */
kauditd_hold_skb(struct sk_buff * skb)567  static void kauditd_hold_skb(struct sk_buff *skb)
568  {
569  	/* at this point it is uncertain if we will ever send this to auditd so
570  	 * try to send the message via printk before we go any further */
571  	kauditd_printk_skb(skb);
572  
573  	/* can we just silently drop the message? */
574  	if (!audit_default) {
575  		kfree_skb(skb);
576  		return;
577  	}
578  
579  	/* if we have room, queue the message */
580  	if (!audit_backlog_limit ||
581  	    skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
582  		skb_queue_tail(&audit_hold_queue, skb);
583  		return;
584  	}
585  
586  	/* we have no other options - drop the message */
587  	audit_log_lost("kauditd hold queue overflow");
588  	kfree_skb(skb);
589  }
590  
591  /**
592   * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
593   * @skb: audit record
594   *
595   * Description:
596   * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
597   * but for some reason we are having problems sending it audit records so
598   * queue the given record and attempt to resend.
599   */
kauditd_retry_skb(struct sk_buff * skb)600  static void kauditd_retry_skb(struct sk_buff *skb)
601  {
602  	/* NOTE: because records should only live in the retry queue for a
603  	 * short period of time, before either being sent or moved to the hold
604  	 * queue, we don't currently enforce a limit on this queue */
605  	skb_queue_tail(&audit_retry_queue, skb);
606  }
607  
608  /**
609   * auditd_reset - Disconnect the auditd connection
610   * @ac: auditd connection state
611   *
612   * Description:
613   * Break the auditd/kauditd connection and move all the queued records into the
614   * hold queue in case auditd reconnects.  It is important to note that the @ac
615   * pointer should never be dereferenced inside this function as it may be NULL
616   * or invalid, you can only compare the memory address!  If @ac is NULL then
617   * the connection will always be reset.
618   */
auditd_reset(const struct auditd_connection * ac)619  static void auditd_reset(const struct auditd_connection *ac)
620  {
621  	unsigned long flags;
622  	struct sk_buff *skb;
623  	struct auditd_connection *ac_old;
624  
625  	/* if it isn't already broken, break the connection */
626  	spin_lock_irqsave(&auditd_conn_lock, flags);
627  	ac_old = rcu_dereference_protected(auditd_conn,
628  					   lockdep_is_held(&auditd_conn_lock));
629  	if (ac && ac != ac_old) {
630  		/* someone already registered a new auditd connection */
631  		spin_unlock_irqrestore(&auditd_conn_lock, flags);
632  		return;
633  	}
634  	rcu_assign_pointer(auditd_conn, NULL);
635  	spin_unlock_irqrestore(&auditd_conn_lock, flags);
636  
637  	if (ac_old)
638  		call_rcu(&ac_old->rcu, auditd_conn_free);
639  
640  	/* flush the retry queue to the hold queue, but don't touch the main
641  	 * queue since we need to process that normally for multicast */
642  	while ((skb = skb_dequeue(&audit_retry_queue)))
643  		kauditd_hold_skb(skb);
644  }
645  
646  /**
647   * auditd_send_unicast_skb - Send a record via unicast to auditd
648   * @skb: audit record
649   *
650   * Description:
651   * Send a skb to the audit daemon, returns positive/zero values on success and
652   * negative values on failure; in all cases the skb will be consumed by this
653   * function.  If the send results in -ECONNREFUSED the connection with auditd
654   * will be reset.  This function may sleep so callers should not hold any locks
655   * where this would cause a problem.
656   */
auditd_send_unicast_skb(struct sk_buff * skb)657  static int auditd_send_unicast_skb(struct sk_buff *skb)
658  {
659  	int rc;
660  	u32 portid;
661  	struct net *net;
662  	struct sock *sk;
663  	struct auditd_connection *ac;
664  
665  	/* NOTE: we can't call netlink_unicast while in the RCU section so
666  	 *       take a reference to the network namespace and grab local
667  	 *       copies of the namespace, the sock, and the portid; the
668  	 *       namespace and sock aren't going to go away while we hold a
669  	 *       reference and if the portid does become invalid after the RCU
670  	 *       section netlink_unicast() should safely return an error */
671  
672  	rcu_read_lock();
673  	ac = rcu_dereference(auditd_conn);
674  	if (!ac) {
675  		rcu_read_unlock();
676  		kfree_skb(skb);
677  		rc = -ECONNREFUSED;
678  		goto err;
679  	}
680  	net = get_net(ac->net);
681  	sk = audit_get_sk(net);
682  	portid = ac->portid;
683  	rcu_read_unlock();
684  
685  	rc = netlink_unicast(sk, skb, portid, 0);
686  	put_net(net);
687  	if (rc < 0)
688  		goto err;
689  
690  	return rc;
691  
692  err:
693  	if (ac && rc == -ECONNREFUSED)
694  		auditd_reset(ac);
695  	return rc;
696  }
697  
698  /**
699   * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
700   * @sk: the sending sock
701   * @portid: the netlink destination
702   * @queue: the skb queue to process
703   * @retry_limit: limit on number of netlink unicast failures
704   * @skb_hook: per-skb hook for additional processing
705   * @err_hook: hook called if the skb fails the netlink unicast send
706   *
707   * Description:
708   * Run through the given queue and attempt to send the audit records to auditd,
709   * returns zero on success, negative values on failure.  It is up to the caller
710   * to ensure that the @sk is valid for the duration of this function.
711   *
712   */
kauditd_send_queue(struct sock * sk,u32 portid,struct sk_buff_head * queue,unsigned int retry_limit,void (* skb_hook)(struct sk_buff * skb),void (* err_hook)(struct sk_buff * skb))713  static int kauditd_send_queue(struct sock *sk, u32 portid,
714  			      struct sk_buff_head *queue,
715  			      unsigned int retry_limit,
716  			      void (*skb_hook)(struct sk_buff *skb),
717  			      void (*err_hook)(struct sk_buff *skb))
718  {
719  	int rc = 0;
720  	struct sk_buff *skb;
721  	unsigned int failed = 0;
722  
723  	/* NOTE: kauditd_thread takes care of all our locking, we just use
724  	 *       the netlink info passed to us (e.g. sk and portid) */
725  
726  	while ((skb = skb_dequeue(queue))) {
727  		/* call the skb_hook for each skb we touch */
728  		if (skb_hook)
729  			(*skb_hook)(skb);
730  
731  		/* can we send to anyone via unicast? */
732  		if (!sk) {
733  			if (err_hook)
734  				(*err_hook)(skb);
735  			continue;
736  		}
737  
738  retry:
739  		/* grab an extra skb reference in case of error */
740  		skb_get(skb);
741  		rc = netlink_unicast(sk, skb, portid, 0);
742  		if (rc < 0) {
743  			/* send failed - try a few times unless fatal error */
744  			if (++failed >= retry_limit ||
745  			    rc == -ECONNREFUSED || rc == -EPERM) {
746  				sk = NULL;
747  				if (err_hook)
748  					(*err_hook)(skb);
749  				if (rc == -EAGAIN)
750  					rc = 0;
751  				/* continue to drain the queue */
752  				continue;
753  			} else
754  				goto retry;
755  		} else {
756  			/* skb sent - drop the extra reference and continue */
757  			consume_skb(skb);
758  			failed = 0;
759  		}
760  	}
761  
762  	return (rc >= 0 ? 0 : rc);
763  }
764  
765  /*
766   * kauditd_send_multicast_skb - Send a record to any multicast listeners
767   * @skb: audit record
768   *
769   * Description:
770   * Write a multicast message to anyone listening in the initial network
771   * namespace.  This function doesn't consume an skb as might be expected since
772   * it has to copy it anyways.
773   */
kauditd_send_multicast_skb(struct sk_buff * skb)774  static void kauditd_send_multicast_skb(struct sk_buff *skb)
775  {
776  	struct sk_buff *copy;
777  	struct sock *sock = audit_get_sk(&init_net);
778  	struct nlmsghdr *nlh;
779  
780  	/* NOTE: we are not taking an additional reference for init_net since
781  	 *       we don't have to worry about it going away */
782  
783  	if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
784  		return;
785  
786  	/*
787  	 * The seemingly wasteful skb_copy() rather than bumping the refcount
788  	 * using skb_get() is necessary because non-standard mods are made to
789  	 * the skb by the original kaudit unicast socket send routine.  The
790  	 * existing auditd daemon assumes this breakage.  Fixing this would
791  	 * require co-ordinating a change in the established protocol between
792  	 * the kaudit kernel subsystem and the auditd userspace code.  There is
793  	 * no reason for new multicast clients to continue with this
794  	 * non-compliance.
795  	 */
796  	copy = skb_copy(skb, GFP_KERNEL);
797  	if (!copy)
798  		return;
799  	nlh = nlmsg_hdr(copy);
800  	nlh->nlmsg_len = skb->len;
801  
802  	nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
803  }
804  
805  /**
806   * kauditd_thread - Worker thread to send audit records to userspace
807   * @dummy: unused
808   */
kauditd_thread(void * dummy)809  static int kauditd_thread(void *dummy)
810  {
811  	int rc;
812  	u32 portid = 0;
813  	struct net *net = NULL;
814  	struct sock *sk = NULL;
815  	struct auditd_connection *ac;
816  
817  #define UNICAST_RETRIES 5
818  
819  	set_freezable();
820  	while (!kthread_should_stop()) {
821  		/* NOTE: see the lock comments in auditd_send_unicast_skb() */
822  		rcu_read_lock();
823  		ac = rcu_dereference(auditd_conn);
824  		if (!ac) {
825  			rcu_read_unlock();
826  			goto main_queue;
827  		}
828  		net = get_net(ac->net);
829  		sk = audit_get_sk(net);
830  		portid = ac->portid;
831  		rcu_read_unlock();
832  
833  		/* attempt to flush the hold queue */
834  		rc = kauditd_send_queue(sk, portid,
835  					&audit_hold_queue, UNICAST_RETRIES,
836  					NULL, kauditd_rehold_skb);
837  		if (rc < 0) {
838  			sk = NULL;
839  			auditd_reset(ac);
840  			goto main_queue;
841  		}
842  
843  		/* attempt to flush the retry queue */
844  		rc = kauditd_send_queue(sk, portid,
845  					&audit_retry_queue, UNICAST_RETRIES,
846  					NULL, kauditd_hold_skb);
847  		if (rc < 0) {
848  			sk = NULL;
849  			auditd_reset(ac);
850  			goto main_queue;
851  		}
852  
853  main_queue:
854  		/* process the main queue - do the multicast send and attempt
855  		 * unicast, dump failed record sends to the retry queue; if
856  		 * sk == NULL due to previous failures we will just do the
857  		 * multicast send and move the record to the hold queue */
858  		rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
859  					kauditd_send_multicast_skb,
860  					(sk ?
861  					 kauditd_retry_skb : kauditd_hold_skb));
862  		if (ac && rc < 0)
863  			auditd_reset(ac);
864  		sk = NULL;
865  
866  		/* drop our netns reference, no auditd sends past this line */
867  		if (net) {
868  			put_net(net);
869  			net = NULL;
870  		}
871  
872  		/* we have processed all the queues so wake everyone */
873  		wake_up(&audit_backlog_wait);
874  
875  		/* NOTE: we want to wake up if there is anything on the queue,
876  		 *       regardless of if an auditd is connected, as we need to
877  		 *       do the multicast send and rotate records from the
878  		 *       main queue to the retry/hold queues */
879  		wait_event_freezable(kauditd_wait,
880  				     (skb_queue_len(&audit_queue) ? 1 : 0));
881  	}
882  
883  	return 0;
884  }
885  
audit_send_list_thread(void * _dest)886  int audit_send_list_thread(void *_dest)
887  {
888  	struct audit_netlink_list *dest = _dest;
889  	struct sk_buff *skb;
890  	struct sock *sk = audit_get_sk(dest->net);
891  
892  	/* wait for parent to finish and send an ACK */
893  	audit_ctl_lock();
894  	audit_ctl_unlock();
895  
896  	while ((skb = __skb_dequeue(&dest->q)) != NULL)
897  		netlink_unicast(sk, skb, dest->portid, 0);
898  
899  	put_net(dest->net);
900  	kfree(dest);
901  
902  	return 0;
903  }
904  
audit_make_reply(int seq,int type,int done,int multi,const void * payload,int size)905  struct sk_buff *audit_make_reply(int seq, int type, int done,
906  				 int multi, const void *payload, int size)
907  {
908  	struct sk_buff	*skb;
909  	struct nlmsghdr	*nlh;
910  	void		*data;
911  	int		flags = multi ? NLM_F_MULTI : 0;
912  	int		t     = done  ? NLMSG_DONE  : type;
913  
914  	skb = nlmsg_new(size, GFP_KERNEL);
915  	if (!skb)
916  		return NULL;
917  
918  	nlh	= nlmsg_put(skb, 0, seq, t, size, flags);
919  	if (!nlh)
920  		goto out_kfree_skb;
921  	data = nlmsg_data(nlh);
922  	memcpy(data, payload, size);
923  	return skb;
924  
925  out_kfree_skb:
926  	kfree_skb(skb);
927  	return NULL;
928  }
929  
audit_free_reply(struct audit_reply * reply)930  static void audit_free_reply(struct audit_reply *reply)
931  {
932  	if (!reply)
933  		return;
934  
935  	kfree_skb(reply->skb);
936  	if (reply->net)
937  		put_net(reply->net);
938  	kfree(reply);
939  }
940  
audit_send_reply_thread(void * arg)941  static int audit_send_reply_thread(void *arg)
942  {
943  	struct audit_reply *reply = (struct audit_reply *)arg;
944  
945  	audit_ctl_lock();
946  	audit_ctl_unlock();
947  
948  	/* Ignore failure. It'll only happen if the sender goes away,
949  	   because our timeout is set to infinite. */
950  	netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0);
951  	reply->skb = NULL;
952  	audit_free_reply(reply);
953  	return 0;
954  }
955  
956  /**
957   * audit_send_reply - send an audit reply message via netlink
958   * @request_skb: skb of request we are replying to (used to target the reply)
959   * @seq: sequence number
960   * @type: audit message type
961   * @done: done (last) flag
962   * @multi: multi-part message flag
963   * @payload: payload data
964   * @size: payload size
965   *
966   * Allocates a skb, builds the netlink message, and sends it to the port id.
967   */
audit_send_reply(struct sk_buff * request_skb,int seq,int type,int done,int multi,const void * payload,int size)968  static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
969  			     int multi, const void *payload, int size)
970  {
971  	struct task_struct *tsk;
972  	struct audit_reply *reply;
973  
974  	reply = kzalloc(sizeof(*reply), GFP_KERNEL);
975  	if (!reply)
976  		return;
977  
978  	reply->skb = audit_make_reply(seq, type, done, multi, payload, size);
979  	if (!reply->skb)
980  		goto err;
981  	reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
982  	reply->portid = NETLINK_CB(request_skb).portid;
983  
984  	tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
985  	if (IS_ERR(tsk))
986  		goto err;
987  
988  	return;
989  
990  err:
991  	audit_free_reply(reply);
992  }
993  
994  /*
995   * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
996   * control messages.
997   */
audit_netlink_ok(struct sk_buff * skb,u16 msg_type)998  static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
999  {
1000  	int err = 0;
1001  
1002  	/* Only support initial user namespace for now. */
1003  	/*
1004  	 * We return ECONNREFUSED because it tricks userspace into thinking
1005  	 * that audit was not configured into the kernel.  Lots of users
1006  	 * configure their PAM stack (because that's what the distro does)
1007  	 * to reject login if unable to send messages to audit.  If we return
1008  	 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1009  	 * configured in and will let login proceed.  If we return EPERM
1010  	 * userspace will reject all logins.  This should be removed when we
1011  	 * support non init namespaces!!
1012  	 */
1013  	if (current_user_ns() != &init_user_ns)
1014  		return -ECONNREFUSED;
1015  
1016  	switch (msg_type) {
1017  	case AUDIT_LIST:
1018  	case AUDIT_ADD:
1019  	case AUDIT_DEL:
1020  		return -EOPNOTSUPP;
1021  	case AUDIT_GET:
1022  	case AUDIT_SET:
1023  	case AUDIT_GET_FEATURE:
1024  	case AUDIT_SET_FEATURE:
1025  	case AUDIT_LIST_RULES:
1026  	case AUDIT_ADD_RULE:
1027  	case AUDIT_DEL_RULE:
1028  	case AUDIT_SIGNAL_INFO:
1029  	case AUDIT_TTY_GET:
1030  	case AUDIT_TTY_SET:
1031  	case AUDIT_TRIM:
1032  	case AUDIT_MAKE_EQUIV:
1033  		/* Only support auditd and auditctl in initial pid namespace
1034  		 * for now. */
1035  		if (task_active_pid_ns(current) != &init_pid_ns)
1036  			return -EPERM;
1037  
1038  		if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1039  			err = -EPERM;
1040  		break;
1041  	case AUDIT_USER:
1042  	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1043  	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1044  		if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1045  			err = -EPERM;
1046  		break;
1047  	default:  /* bad msg */
1048  		err = -EINVAL;
1049  	}
1050  
1051  	return err;
1052  }
1053  
audit_log_common_recv_msg(struct audit_context * context,struct audit_buffer ** ab,u16 msg_type)1054  static void audit_log_common_recv_msg(struct audit_context *context,
1055  					struct audit_buffer **ab, u16 msg_type)
1056  {
1057  	uid_t uid = from_kuid(&init_user_ns, current_uid());
1058  	pid_t pid = task_tgid_nr(current);
1059  
1060  	if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1061  		*ab = NULL;
1062  		return;
1063  	}
1064  
1065  	*ab = audit_log_start(context, GFP_KERNEL, msg_type);
1066  	if (unlikely(!*ab))
1067  		return;
1068  	audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1069  	audit_log_session_info(*ab);
1070  	audit_log_task_context(*ab);
1071  }
1072  
audit_log_user_recv_msg(struct audit_buffer ** ab,u16 msg_type)1073  static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1074  					   u16 msg_type)
1075  {
1076  	audit_log_common_recv_msg(NULL, ab, msg_type);
1077  }
1078  
is_audit_feature_set(int i)1079  int is_audit_feature_set(int i)
1080  {
1081  	return af.features & AUDIT_FEATURE_TO_MASK(i);
1082  }
1083  
1084  
audit_get_feature(struct sk_buff * skb)1085  static int audit_get_feature(struct sk_buff *skb)
1086  {
1087  	u32 seq;
1088  
1089  	seq = nlmsg_hdr(skb)->nlmsg_seq;
1090  
1091  	audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1092  
1093  	return 0;
1094  }
1095  
audit_log_feature_change(int which,u32 old_feature,u32 new_feature,u32 old_lock,u32 new_lock,int res)1096  static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1097  				     u32 old_lock, u32 new_lock, int res)
1098  {
1099  	struct audit_buffer *ab;
1100  
1101  	if (audit_enabled == AUDIT_OFF)
1102  		return;
1103  
1104  	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1105  	if (!ab)
1106  		return;
1107  	audit_log_task_info(ab);
1108  	audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1109  			 audit_feature_names[which], !!old_feature, !!new_feature,
1110  			 !!old_lock, !!new_lock, res);
1111  	audit_log_end(ab);
1112  }
1113  
audit_set_feature(struct audit_features * uaf)1114  static int audit_set_feature(struct audit_features *uaf)
1115  {
1116  	int i;
1117  
1118  	BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1119  
1120  	/* if there is ever a version 2 we should handle that here */
1121  
1122  	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1123  		u32 feature = AUDIT_FEATURE_TO_MASK(i);
1124  		u32 old_feature, new_feature, old_lock, new_lock;
1125  
1126  		/* if we are not changing this feature, move along */
1127  		if (!(feature & uaf->mask))
1128  			continue;
1129  
1130  		old_feature = af.features & feature;
1131  		new_feature = uaf->features & feature;
1132  		new_lock = (uaf->lock | af.lock) & feature;
1133  		old_lock = af.lock & feature;
1134  
1135  		/* are we changing a locked feature? */
1136  		if (old_lock && (new_feature != old_feature)) {
1137  			audit_log_feature_change(i, old_feature, new_feature,
1138  						 old_lock, new_lock, 0);
1139  			return -EPERM;
1140  		}
1141  	}
1142  	/* nothing invalid, do the changes */
1143  	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1144  		u32 feature = AUDIT_FEATURE_TO_MASK(i);
1145  		u32 old_feature, new_feature, old_lock, new_lock;
1146  
1147  		/* if we are not changing this feature, move along */
1148  		if (!(feature & uaf->mask))
1149  			continue;
1150  
1151  		old_feature = af.features & feature;
1152  		new_feature = uaf->features & feature;
1153  		old_lock = af.lock & feature;
1154  		new_lock = (uaf->lock | af.lock) & feature;
1155  
1156  		if (new_feature != old_feature)
1157  			audit_log_feature_change(i, old_feature, new_feature,
1158  						 old_lock, new_lock, 1);
1159  
1160  		if (new_feature)
1161  			af.features |= feature;
1162  		else
1163  			af.features &= ~feature;
1164  		af.lock |= new_lock;
1165  	}
1166  
1167  	return 0;
1168  }
1169  
audit_replace(struct pid * pid)1170  static int audit_replace(struct pid *pid)
1171  {
1172  	pid_t pvnr;
1173  	struct sk_buff *skb;
1174  
1175  	pvnr = pid_vnr(pid);
1176  	skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1177  	if (!skb)
1178  		return -ENOMEM;
1179  	return auditd_send_unicast_skb(skb);
1180  }
1181  
audit_receive_msg(struct sk_buff * skb,struct nlmsghdr * nlh)1182  static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
1183  {
1184  	u32			seq;
1185  	void			*data;
1186  	int			data_len;
1187  	int			err;
1188  	struct audit_buffer	*ab;
1189  	u16			msg_type = nlh->nlmsg_type;
1190  	struct audit_sig_info   *sig_data;
1191  	char			*ctx = NULL;
1192  	u32			len;
1193  
1194  	err = audit_netlink_ok(skb, msg_type);
1195  	if (err)
1196  		return err;
1197  
1198  	seq  = nlh->nlmsg_seq;
1199  	data = nlmsg_data(nlh);
1200  	data_len = nlmsg_len(nlh);
1201  
1202  	switch (msg_type) {
1203  	case AUDIT_GET: {
1204  		struct audit_status	s;
1205  		memset(&s, 0, sizeof(s));
1206  		s.enabled		   = audit_enabled;
1207  		s.failure		   = audit_failure;
1208  		/* NOTE: use pid_vnr() so the PID is relative to the current
1209  		 *       namespace */
1210  		s.pid			   = auditd_pid_vnr();
1211  		s.rate_limit		   = audit_rate_limit;
1212  		s.backlog_limit		   = audit_backlog_limit;
1213  		s.lost			   = atomic_read(&audit_lost);
1214  		s.backlog		   = skb_queue_len(&audit_queue);
1215  		s.feature_bitmap	   = AUDIT_FEATURE_BITMAP_ALL;
1216  		s.backlog_wait_time	   = audit_backlog_wait_time;
1217  		s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual);
1218  		audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1219  		break;
1220  	}
1221  	case AUDIT_SET: {
1222  		struct audit_status	s;
1223  		memset(&s, 0, sizeof(s));
1224  		/* guard against past and future API changes */
1225  		memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1226  		if (s.mask & AUDIT_STATUS_ENABLED) {
1227  			err = audit_set_enabled(s.enabled);
1228  			if (err < 0)
1229  				return err;
1230  		}
1231  		if (s.mask & AUDIT_STATUS_FAILURE) {
1232  			err = audit_set_failure(s.failure);
1233  			if (err < 0)
1234  				return err;
1235  		}
1236  		if (s.mask & AUDIT_STATUS_PID) {
1237  			/* NOTE: we are using the vnr PID functions below
1238  			 *       because the s.pid value is relative to the
1239  			 *       namespace of the caller; at present this
1240  			 *       doesn't matter much since you can really only
1241  			 *       run auditd from the initial pid namespace, but
1242  			 *       something to keep in mind if this changes */
1243  			pid_t new_pid = s.pid;
1244  			pid_t auditd_pid;
1245  			struct pid *req_pid = task_tgid(current);
1246  
1247  			/* Sanity check - PID values must match. Setting
1248  			 * pid to 0 is how auditd ends auditing. */
1249  			if (new_pid && (new_pid != pid_vnr(req_pid)))
1250  				return -EINVAL;
1251  
1252  			/* test the auditd connection */
1253  			audit_replace(req_pid);
1254  
1255  			auditd_pid = auditd_pid_vnr();
1256  			if (auditd_pid) {
1257  				/* replacing a healthy auditd is not allowed */
1258  				if (new_pid) {
1259  					audit_log_config_change("audit_pid",
1260  							new_pid, auditd_pid, 0);
1261  					return -EEXIST;
1262  				}
1263  				/* only current auditd can unregister itself */
1264  				if (pid_vnr(req_pid) != auditd_pid) {
1265  					audit_log_config_change("audit_pid",
1266  							new_pid, auditd_pid, 0);
1267  					return -EACCES;
1268  				}
1269  			}
1270  
1271  			if (new_pid) {
1272  				/* register a new auditd connection */
1273  				err = auditd_set(req_pid,
1274  						 NETLINK_CB(skb).portid,
1275  						 sock_net(NETLINK_CB(skb).sk));
1276  				if (audit_enabled != AUDIT_OFF)
1277  					audit_log_config_change("audit_pid",
1278  								new_pid,
1279  								auditd_pid,
1280  								err ? 0 : 1);
1281  				if (err)
1282  					return err;
1283  
1284  				/* try to process any backlog */
1285  				wake_up_interruptible(&kauditd_wait);
1286  			} else {
1287  				if (audit_enabled != AUDIT_OFF)
1288  					audit_log_config_change("audit_pid",
1289  								new_pid,
1290  								auditd_pid, 1);
1291  
1292  				/* unregister the auditd connection */
1293  				auditd_reset(NULL);
1294  			}
1295  		}
1296  		if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1297  			err = audit_set_rate_limit(s.rate_limit);
1298  			if (err < 0)
1299  				return err;
1300  		}
1301  		if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1302  			err = audit_set_backlog_limit(s.backlog_limit);
1303  			if (err < 0)
1304  				return err;
1305  		}
1306  		if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1307  			if (sizeof(s) > (size_t)nlh->nlmsg_len)
1308  				return -EINVAL;
1309  			if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1310  				return -EINVAL;
1311  			err = audit_set_backlog_wait_time(s.backlog_wait_time);
1312  			if (err < 0)
1313  				return err;
1314  		}
1315  		if (s.mask == AUDIT_STATUS_LOST) {
1316  			u32 lost = atomic_xchg(&audit_lost, 0);
1317  
1318  			audit_log_config_change("lost", 0, lost, 1);
1319  			return lost;
1320  		}
1321  		if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1322  			u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0);
1323  
1324  			audit_log_config_change("backlog_wait_time_actual", 0, actual, 1);
1325  			return actual;
1326  		}
1327  		break;
1328  	}
1329  	case AUDIT_GET_FEATURE:
1330  		err = audit_get_feature(skb);
1331  		if (err)
1332  			return err;
1333  		break;
1334  	case AUDIT_SET_FEATURE:
1335  		if (data_len < sizeof(struct audit_features))
1336  			return -EINVAL;
1337  		err = audit_set_feature(data);
1338  		if (err)
1339  			return err;
1340  		break;
1341  	case AUDIT_USER:
1342  	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1343  	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1344  		if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1345  			return 0;
1346  		/* exit early if there isn't at least one character to print */
1347  		if (data_len < 2)
1348  			return -EINVAL;
1349  
1350  		err = audit_filter(msg_type, AUDIT_FILTER_USER);
1351  		if (err == 1) { /* match or error */
1352  			char *str = data;
1353  
1354  			err = 0;
1355  			if (msg_type == AUDIT_USER_TTY) {
1356  				err = tty_audit_push();
1357  				if (err)
1358  					break;
1359  			}
1360  			audit_log_user_recv_msg(&ab, msg_type);
1361  			if (msg_type != AUDIT_USER_TTY) {
1362  				/* ensure NULL termination */
1363  				str[data_len - 1] = '\0';
1364  				audit_log_format(ab, " msg='%.*s'",
1365  						 AUDIT_MESSAGE_TEXT_MAX,
1366  						 str);
1367  			} else {
1368  				audit_log_format(ab, " data=");
1369  				if (data_len > 0 && str[data_len - 1] == '\0')
1370  					data_len--;
1371  				audit_log_n_untrustedstring(ab, str, data_len);
1372  			}
1373  			audit_log_end(ab);
1374  		}
1375  		break;
1376  	case AUDIT_ADD_RULE:
1377  	case AUDIT_DEL_RULE:
1378  		if (data_len < sizeof(struct audit_rule_data))
1379  			return -EINVAL;
1380  		if (audit_enabled == AUDIT_LOCKED) {
1381  			audit_log_common_recv_msg(audit_context(), &ab,
1382  						  AUDIT_CONFIG_CHANGE);
1383  			audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1384  					 msg_type == AUDIT_ADD_RULE ?
1385  						"add_rule" : "remove_rule",
1386  					 audit_enabled);
1387  			audit_log_end(ab);
1388  			return -EPERM;
1389  		}
1390  		err = audit_rule_change(msg_type, seq, data, data_len);
1391  		break;
1392  	case AUDIT_LIST_RULES:
1393  		err = audit_list_rules_send(skb, seq);
1394  		break;
1395  	case AUDIT_TRIM:
1396  		audit_trim_trees();
1397  		audit_log_common_recv_msg(audit_context(), &ab,
1398  					  AUDIT_CONFIG_CHANGE);
1399  		audit_log_format(ab, " op=trim res=1");
1400  		audit_log_end(ab);
1401  		break;
1402  	case AUDIT_MAKE_EQUIV: {
1403  		void *bufp = data;
1404  		u32 sizes[2];
1405  		size_t msglen = data_len;
1406  		char *old, *new;
1407  
1408  		err = -EINVAL;
1409  		if (msglen < 2 * sizeof(u32))
1410  			break;
1411  		memcpy(sizes, bufp, 2 * sizeof(u32));
1412  		bufp += 2 * sizeof(u32);
1413  		msglen -= 2 * sizeof(u32);
1414  		old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1415  		if (IS_ERR(old)) {
1416  			err = PTR_ERR(old);
1417  			break;
1418  		}
1419  		new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1420  		if (IS_ERR(new)) {
1421  			err = PTR_ERR(new);
1422  			kfree(old);
1423  			break;
1424  		}
1425  		/* OK, here comes... */
1426  		err = audit_tag_tree(old, new);
1427  
1428  		audit_log_common_recv_msg(audit_context(), &ab,
1429  					  AUDIT_CONFIG_CHANGE);
1430  		audit_log_format(ab, " op=make_equiv old=");
1431  		audit_log_untrustedstring(ab, old);
1432  		audit_log_format(ab, " new=");
1433  		audit_log_untrustedstring(ab, new);
1434  		audit_log_format(ab, " res=%d", !err);
1435  		audit_log_end(ab);
1436  		kfree(old);
1437  		kfree(new);
1438  		break;
1439  	}
1440  	case AUDIT_SIGNAL_INFO:
1441  		len = 0;
1442  		if (audit_sig_sid) {
1443  			err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1444  			if (err)
1445  				return err;
1446  		}
1447  		sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1448  		if (!sig_data) {
1449  			if (audit_sig_sid)
1450  				security_release_secctx(ctx, len);
1451  			return -ENOMEM;
1452  		}
1453  		sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1454  		sig_data->pid = audit_sig_pid;
1455  		if (audit_sig_sid) {
1456  			memcpy(sig_data->ctx, ctx, len);
1457  			security_release_secctx(ctx, len);
1458  		}
1459  		audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1460  				 sig_data, sizeof(*sig_data) + len);
1461  		kfree(sig_data);
1462  		break;
1463  	case AUDIT_TTY_GET: {
1464  		struct audit_tty_status s;
1465  		unsigned int t;
1466  
1467  		t = READ_ONCE(current->signal->audit_tty);
1468  		s.enabled = t & AUDIT_TTY_ENABLE;
1469  		s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1470  
1471  		audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1472  		break;
1473  	}
1474  	case AUDIT_TTY_SET: {
1475  		struct audit_tty_status s, old;
1476  		struct audit_buffer	*ab;
1477  		unsigned int t;
1478  
1479  		memset(&s, 0, sizeof(s));
1480  		/* guard against past and future API changes */
1481  		memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1482  		/* check if new data is valid */
1483  		if ((s.enabled != 0 && s.enabled != 1) ||
1484  		    (s.log_passwd != 0 && s.log_passwd != 1))
1485  			err = -EINVAL;
1486  
1487  		if (err)
1488  			t = READ_ONCE(current->signal->audit_tty);
1489  		else {
1490  			t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1491  			t = xchg(&current->signal->audit_tty, t);
1492  		}
1493  		old.enabled = t & AUDIT_TTY_ENABLE;
1494  		old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1495  
1496  		audit_log_common_recv_msg(audit_context(), &ab,
1497  					  AUDIT_CONFIG_CHANGE);
1498  		audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1499  				 " old-log_passwd=%d new-log_passwd=%d res=%d",
1500  				 old.enabled, s.enabled, old.log_passwd,
1501  				 s.log_passwd, !err);
1502  		audit_log_end(ab);
1503  		break;
1504  	}
1505  	default:
1506  		err = -EINVAL;
1507  		break;
1508  	}
1509  
1510  	return err < 0 ? err : 0;
1511  }
1512  
1513  /**
1514   * audit_receive - receive messages from a netlink control socket
1515   * @skb: the message buffer
1516   *
1517   * Parse the provided skb and deal with any messages that may be present,
1518   * malformed skbs are discarded.
1519   */
audit_receive(struct sk_buff * skb)1520  static void audit_receive(struct sk_buff  *skb)
1521  {
1522  	struct nlmsghdr *nlh;
1523  	/*
1524  	 * len MUST be signed for nlmsg_next to be able to dec it below 0
1525  	 * if the nlmsg_len was not aligned
1526  	 */
1527  	int len;
1528  	int err;
1529  
1530  	nlh = nlmsg_hdr(skb);
1531  	len = skb->len;
1532  
1533  	audit_ctl_lock();
1534  	while (nlmsg_ok(nlh, len)) {
1535  		err = audit_receive_msg(skb, nlh);
1536  		/* if err or if this message says it wants a response */
1537  		if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1538  			netlink_ack(skb, nlh, err, NULL);
1539  
1540  		nlh = nlmsg_next(nlh, &len);
1541  	}
1542  	audit_ctl_unlock();
1543  
1544  	/* can't block with the ctrl lock, so penalize the sender now */
1545  	if (audit_backlog_limit &&
1546  	    (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1547  		DECLARE_WAITQUEUE(wait, current);
1548  
1549  		/* wake kauditd to try and flush the queue */
1550  		wake_up_interruptible(&kauditd_wait);
1551  
1552  		add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1553  		set_current_state(TASK_UNINTERRUPTIBLE);
1554  		schedule_timeout(audit_backlog_wait_time);
1555  		remove_wait_queue(&audit_backlog_wait, &wait);
1556  	}
1557  }
1558  
1559  /* Log information about who is connecting to the audit multicast socket */
audit_log_multicast(int group,const char * op,int err)1560  static void audit_log_multicast(int group, const char *op, int err)
1561  {
1562  	const struct cred *cred;
1563  	struct tty_struct *tty;
1564  	char comm[sizeof(current->comm)];
1565  	struct audit_buffer *ab;
1566  
1567  	if (!audit_enabled)
1568  		return;
1569  
1570  	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER);
1571  	if (!ab)
1572  		return;
1573  
1574  	cred = current_cred();
1575  	tty = audit_get_tty();
1576  	audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u",
1577  			 task_pid_nr(current),
1578  			 from_kuid(&init_user_ns, cred->uid),
1579  			 from_kuid(&init_user_ns, audit_get_loginuid(current)),
1580  			 tty ? tty_name(tty) : "(none)",
1581  			 audit_get_sessionid(current));
1582  	audit_put_tty(tty);
1583  	audit_log_task_context(ab); /* subj= */
1584  	audit_log_format(ab, " comm=");
1585  	audit_log_untrustedstring(ab, get_task_comm(comm, current));
1586  	audit_log_d_path_exe(ab, current->mm); /* exe= */
1587  	audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
1588  	audit_log_end(ab);
1589  }
1590  
1591  /* Run custom bind function on netlink socket group connect or bind requests. */
audit_multicast_bind(struct net * net,int group)1592  static int audit_multicast_bind(struct net *net, int group)
1593  {
1594  	int err = 0;
1595  
1596  	if (!capable(CAP_AUDIT_READ))
1597  		err = -EPERM;
1598  	audit_log_multicast(group, "connect", err);
1599  	return err;
1600  }
1601  
audit_multicast_unbind(struct net * net,int group)1602  static void audit_multicast_unbind(struct net *net, int group)
1603  {
1604  	audit_log_multicast(group, "disconnect", 0);
1605  }
1606  
audit_net_init(struct net * net)1607  static int __net_init audit_net_init(struct net *net)
1608  {
1609  	struct netlink_kernel_cfg cfg = {
1610  		.input	= audit_receive,
1611  		.bind	= audit_multicast_bind,
1612  		.unbind	= audit_multicast_unbind,
1613  		.flags	= NL_CFG_F_NONROOT_RECV,
1614  		.groups	= AUDIT_NLGRP_MAX,
1615  	};
1616  
1617  	struct audit_net *aunet = net_generic(net, audit_net_id);
1618  
1619  	aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1620  	if (aunet->sk == NULL) {
1621  		audit_panic("cannot initialize netlink socket in namespace");
1622  		return -ENOMEM;
1623  	}
1624  	/* limit the timeout in case auditd is blocked/stopped */
1625  	aunet->sk->sk_sndtimeo = HZ / 10;
1626  
1627  	return 0;
1628  }
1629  
audit_net_exit(struct net * net)1630  static void __net_exit audit_net_exit(struct net *net)
1631  {
1632  	struct audit_net *aunet = net_generic(net, audit_net_id);
1633  
1634  	/* NOTE: you would think that we would want to check the auditd
1635  	 * connection and potentially reset it here if it lives in this
1636  	 * namespace, but since the auditd connection tracking struct holds a
1637  	 * reference to this namespace (see auditd_set()) we are only ever
1638  	 * going to get here after that connection has been released */
1639  
1640  	netlink_kernel_release(aunet->sk);
1641  }
1642  
1643  static struct pernet_operations audit_net_ops __net_initdata = {
1644  	.init = audit_net_init,
1645  	.exit = audit_net_exit,
1646  	.id = &audit_net_id,
1647  	.size = sizeof(struct audit_net),
1648  };
1649  
1650  /* Initialize audit support at boot time. */
audit_init(void)1651  static int __init audit_init(void)
1652  {
1653  	int i;
1654  
1655  	if (audit_initialized == AUDIT_DISABLED)
1656  		return 0;
1657  
1658  	audit_buffer_cache = kmem_cache_create("audit_buffer",
1659  					       sizeof(struct audit_buffer),
1660  					       0, SLAB_PANIC, NULL);
1661  
1662  	skb_queue_head_init(&audit_queue);
1663  	skb_queue_head_init(&audit_retry_queue);
1664  	skb_queue_head_init(&audit_hold_queue);
1665  
1666  	for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1667  		INIT_LIST_HEAD(&audit_inode_hash[i]);
1668  
1669  	mutex_init(&audit_cmd_mutex.lock);
1670  	audit_cmd_mutex.owner = NULL;
1671  
1672  	pr_info("initializing netlink subsys (%s)\n",
1673  		audit_default ? "enabled" : "disabled");
1674  	register_pernet_subsys(&audit_net_ops);
1675  
1676  	audit_initialized = AUDIT_INITIALIZED;
1677  
1678  	kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1679  	if (IS_ERR(kauditd_task)) {
1680  		int err = PTR_ERR(kauditd_task);
1681  		panic("audit: failed to start the kauditd thread (%d)\n", err);
1682  	}
1683  
1684  	audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1685  		"state=initialized audit_enabled=%u res=1",
1686  		 audit_enabled);
1687  
1688  	return 0;
1689  }
1690  postcore_initcall(audit_init);
1691  
1692  /*
1693   * Process kernel command-line parameter at boot time.
1694   * audit={0|off} or audit={1|on}.
1695   */
audit_enable(char * str)1696  static int __init audit_enable(char *str)
1697  {
1698  	if (!strcasecmp(str, "off") || !strcmp(str, "0"))
1699  		audit_default = AUDIT_OFF;
1700  	else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1701  		audit_default = AUDIT_ON;
1702  	else {
1703  		pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1704  		audit_default = AUDIT_ON;
1705  	}
1706  
1707  	if (audit_default == AUDIT_OFF)
1708  		audit_initialized = AUDIT_DISABLED;
1709  	if (audit_set_enabled(audit_default))
1710  		pr_err("audit: error setting audit state (%d)\n",
1711  		       audit_default);
1712  
1713  	pr_info("%s\n", audit_default ?
1714  		"enabled (after initialization)" : "disabled (until reboot)");
1715  
1716  	return 1;
1717  }
1718  __setup("audit=", audit_enable);
1719  
1720  /* Process kernel command-line parameter at boot time.
1721   * audit_backlog_limit=<n> */
audit_backlog_limit_set(char * str)1722  static int __init audit_backlog_limit_set(char *str)
1723  {
1724  	u32 audit_backlog_limit_arg;
1725  
1726  	pr_info("audit_backlog_limit: ");
1727  	if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1728  		pr_cont("using default of %u, unable to parse %s\n",
1729  			audit_backlog_limit, str);
1730  		return 1;
1731  	}
1732  
1733  	audit_backlog_limit = audit_backlog_limit_arg;
1734  	pr_cont("%d\n", audit_backlog_limit);
1735  
1736  	return 1;
1737  }
1738  __setup("audit_backlog_limit=", audit_backlog_limit_set);
1739  
audit_buffer_free(struct audit_buffer * ab)1740  static void audit_buffer_free(struct audit_buffer *ab)
1741  {
1742  	if (!ab)
1743  		return;
1744  
1745  	kfree_skb(ab->skb);
1746  	kmem_cache_free(audit_buffer_cache, ab);
1747  }
1748  
audit_buffer_alloc(struct audit_context * ctx,gfp_t gfp_mask,int type)1749  static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1750  					       gfp_t gfp_mask, int type)
1751  {
1752  	struct audit_buffer *ab;
1753  
1754  	ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1755  	if (!ab)
1756  		return NULL;
1757  
1758  	ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1759  	if (!ab->skb)
1760  		goto err;
1761  	if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1762  		goto err;
1763  
1764  	ab->ctx = ctx;
1765  	ab->gfp_mask = gfp_mask;
1766  
1767  	return ab;
1768  
1769  err:
1770  	audit_buffer_free(ab);
1771  	return NULL;
1772  }
1773  
1774  /**
1775   * audit_serial - compute a serial number for the audit record
1776   *
1777   * Compute a serial number for the audit record.  Audit records are
1778   * written to user-space as soon as they are generated, so a complete
1779   * audit record may be written in several pieces.  The timestamp of the
1780   * record and this serial number are used by the user-space tools to
1781   * determine which pieces belong to the same audit record.  The
1782   * (timestamp,serial) tuple is unique for each syscall and is live from
1783   * syscall entry to syscall exit.
1784   *
1785   * NOTE: Another possibility is to store the formatted records off the
1786   * audit context (for those records that have a context), and emit them
1787   * all at syscall exit.  However, this could delay the reporting of
1788   * significant errors until syscall exit (or never, if the system
1789   * halts).
1790   */
audit_serial(void)1791  unsigned int audit_serial(void)
1792  {
1793  	static atomic_t serial = ATOMIC_INIT(0);
1794  
1795  	return atomic_add_return(1, &serial);
1796  }
1797  
audit_get_stamp(struct audit_context * ctx,struct timespec64 * t,unsigned int * serial)1798  static inline void audit_get_stamp(struct audit_context *ctx,
1799  				   struct timespec64 *t, unsigned int *serial)
1800  {
1801  	if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1802  		ktime_get_coarse_real_ts64(t);
1803  		*serial = audit_serial();
1804  	}
1805  }
1806  
1807  /**
1808   * audit_log_start - obtain an audit buffer
1809   * @ctx: audit_context (may be NULL)
1810   * @gfp_mask: type of allocation
1811   * @type: audit message type
1812   *
1813   * Returns audit_buffer pointer on success or NULL on error.
1814   *
1815   * Obtain an audit buffer.  This routine does locking to obtain the
1816   * audit buffer, but then no locking is required for calls to
1817   * audit_log_*format.  If the task (ctx) is a task that is currently in a
1818   * syscall, then the syscall is marked as auditable and an audit record
1819   * will be written at syscall exit.  If there is no associated task, then
1820   * task context (ctx) should be NULL.
1821   */
audit_log_start(struct audit_context * ctx,gfp_t gfp_mask,int type)1822  struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1823  				     int type)
1824  {
1825  	struct audit_buffer *ab;
1826  	struct timespec64 t;
1827  	unsigned int serial;
1828  
1829  	if (audit_initialized != AUDIT_INITIALIZED)
1830  		return NULL;
1831  
1832  	if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1833  		return NULL;
1834  
1835  	/* NOTE: don't ever fail/sleep on these two conditions:
1836  	 * 1. auditd generated record - since we need auditd to drain the
1837  	 *    queue; also, when we are checking for auditd, compare PIDs using
1838  	 *    task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1839  	 *    using a PID anchored in the caller's namespace
1840  	 * 2. generator holding the audit_cmd_mutex - we don't want to block
1841  	 *    while holding the mutex, although we do penalize the sender
1842  	 *    later in audit_receive() when it is safe to block
1843  	 */
1844  	if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1845  		long stime = audit_backlog_wait_time;
1846  
1847  		while (audit_backlog_limit &&
1848  		       (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1849  			/* wake kauditd to try and flush the queue */
1850  			wake_up_interruptible(&kauditd_wait);
1851  
1852  			/* sleep if we are allowed and we haven't exhausted our
1853  			 * backlog wait limit */
1854  			if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1855  				long rtime = stime;
1856  
1857  				DECLARE_WAITQUEUE(wait, current);
1858  
1859  				add_wait_queue_exclusive(&audit_backlog_wait,
1860  							 &wait);
1861  				set_current_state(TASK_UNINTERRUPTIBLE);
1862  				stime = schedule_timeout(rtime);
1863  				atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
1864  				remove_wait_queue(&audit_backlog_wait, &wait);
1865  			} else {
1866  				if (audit_rate_check() && printk_ratelimit())
1867  					pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1868  						skb_queue_len(&audit_queue),
1869  						audit_backlog_limit);
1870  				audit_log_lost("backlog limit exceeded");
1871  				return NULL;
1872  			}
1873  		}
1874  	}
1875  
1876  	ab = audit_buffer_alloc(ctx, gfp_mask, type);
1877  	if (!ab) {
1878  		audit_log_lost("out of memory in audit_log_start");
1879  		return NULL;
1880  	}
1881  
1882  	audit_get_stamp(ab->ctx, &t, &serial);
1883  	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1884  			 (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
1885  
1886  	return ab;
1887  }
1888  
1889  /**
1890   * audit_expand - expand skb in the audit buffer
1891   * @ab: audit_buffer
1892   * @extra: space to add at tail of the skb
1893   *
1894   * Returns 0 (no space) on failed expansion, or available space if
1895   * successful.
1896   */
audit_expand(struct audit_buffer * ab,int extra)1897  static inline int audit_expand(struct audit_buffer *ab, int extra)
1898  {
1899  	struct sk_buff *skb = ab->skb;
1900  	int oldtail = skb_tailroom(skb);
1901  	int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1902  	int newtail = skb_tailroom(skb);
1903  
1904  	if (ret < 0) {
1905  		audit_log_lost("out of memory in audit_expand");
1906  		return 0;
1907  	}
1908  
1909  	skb->truesize += newtail - oldtail;
1910  	return newtail;
1911  }
1912  
1913  /*
1914   * Format an audit message into the audit buffer.  If there isn't enough
1915   * room in the audit buffer, more room will be allocated and vsnprint
1916   * will be called a second time.  Currently, we assume that a printk
1917   * can't format message larger than 1024 bytes, so we don't either.
1918   */
audit_log_vformat(struct audit_buffer * ab,const char * fmt,va_list args)1919  static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1920  			      va_list args)
1921  {
1922  	int len, avail;
1923  	struct sk_buff *skb;
1924  	va_list args2;
1925  
1926  	if (!ab)
1927  		return;
1928  
1929  	BUG_ON(!ab->skb);
1930  	skb = ab->skb;
1931  	avail = skb_tailroom(skb);
1932  	if (avail == 0) {
1933  		avail = audit_expand(ab, AUDIT_BUFSIZ);
1934  		if (!avail)
1935  			goto out;
1936  	}
1937  	va_copy(args2, args);
1938  	len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1939  	if (len >= avail) {
1940  		/* The printk buffer is 1024 bytes long, so if we get
1941  		 * here and AUDIT_BUFSIZ is at least 1024, then we can
1942  		 * log everything that printk could have logged. */
1943  		avail = audit_expand(ab,
1944  			max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1945  		if (!avail)
1946  			goto out_va_end;
1947  		len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1948  	}
1949  	if (len > 0)
1950  		skb_put(skb, len);
1951  out_va_end:
1952  	va_end(args2);
1953  out:
1954  	return;
1955  }
1956  
1957  /**
1958   * audit_log_format - format a message into the audit buffer.
1959   * @ab: audit_buffer
1960   * @fmt: format string
1961   * @...: optional parameters matching @fmt string
1962   *
1963   * All the work is done in audit_log_vformat.
1964   */
audit_log_format(struct audit_buffer * ab,const char * fmt,...)1965  void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1966  {
1967  	va_list args;
1968  
1969  	if (!ab)
1970  		return;
1971  	va_start(args, fmt);
1972  	audit_log_vformat(ab, fmt, args);
1973  	va_end(args);
1974  }
1975  
1976  /**
1977   * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
1978   * @ab: the audit_buffer
1979   * @buf: buffer to convert to hex
1980   * @len: length of @buf to be converted
1981   *
1982   * No return value; failure to expand is silently ignored.
1983   *
1984   * This function will take the passed buf and convert it into a string of
1985   * ascii hex digits. The new string is placed onto the skb.
1986   */
audit_log_n_hex(struct audit_buffer * ab,const unsigned char * buf,size_t len)1987  void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1988  		size_t len)
1989  {
1990  	int i, avail, new_len;
1991  	unsigned char *ptr;
1992  	struct sk_buff *skb;
1993  
1994  	if (!ab)
1995  		return;
1996  
1997  	BUG_ON(!ab->skb);
1998  	skb = ab->skb;
1999  	avail = skb_tailroom(skb);
2000  	new_len = len<<1;
2001  	if (new_len >= avail) {
2002  		/* Round the buffer request up to the next multiple */
2003  		new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
2004  		avail = audit_expand(ab, new_len);
2005  		if (!avail)
2006  			return;
2007  	}
2008  
2009  	ptr = skb_tail_pointer(skb);
2010  	for (i = 0; i < len; i++)
2011  		ptr = hex_byte_pack_upper(ptr, buf[i]);
2012  	*ptr = 0;
2013  	skb_put(skb, len << 1); /* new string is twice the old string */
2014  }
2015  
2016  /*
2017   * Format a string of no more than slen characters into the audit buffer,
2018   * enclosed in quote marks.
2019   */
audit_log_n_string(struct audit_buffer * ab,const char * string,size_t slen)2020  void audit_log_n_string(struct audit_buffer *ab, const char *string,
2021  			size_t slen)
2022  {
2023  	int avail, new_len;
2024  	unsigned char *ptr;
2025  	struct sk_buff *skb;
2026  
2027  	if (!ab)
2028  		return;
2029  
2030  	BUG_ON(!ab->skb);
2031  	skb = ab->skb;
2032  	avail = skb_tailroom(skb);
2033  	new_len = slen + 3;	/* enclosing quotes + null terminator */
2034  	if (new_len > avail) {
2035  		avail = audit_expand(ab, new_len);
2036  		if (!avail)
2037  			return;
2038  	}
2039  	ptr = skb_tail_pointer(skb);
2040  	*ptr++ = '"';
2041  	memcpy(ptr, string, slen);
2042  	ptr += slen;
2043  	*ptr++ = '"';
2044  	*ptr = 0;
2045  	skb_put(skb, slen + 2);	/* don't include null terminator */
2046  }
2047  
2048  /**
2049   * audit_string_contains_control - does a string need to be logged in hex
2050   * @string: string to be checked
2051   * @len: max length of the string to check
2052   */
audit_string_contains_control(const char * string,size_t len)2053  bool audit_string_contains_control(const char *string, size_t len)
2054  {
2055  	const unsigned char *p;
2056  	for (p = string; p < (const unsigned char *)string + len; p++) {
2057  		if (*p == '"' || *p < 0x21 || *p > 0x7e)
2058  			return true;
2059  	}
2060  	return false;
2061  }
2062  
2063  /**
2064   * audit_log_n_untrustedstring - log a string that may contain random characters
2065   * @ab: audit_buffer
2066   * @len: length of string (not including trailing null)
2067   * @string: string to be logged
2068   *
2069   * This code will escape a string that is passed to it if the string
2070   * contains a control character, unprintable character, double quote mark,
2071   * or a space. Unescaped strings will start and end with a double quote mark.
2072   * Strings that are escaped are printed in hex (2 digits per char).
2073   *
2074   * The caller specifies the number of characters in the string to log, which may
2075   * or may not be the entire string.
2076   */
audit_log_n_untrustedstring(struct audit_buffer * ab,const char * string,size_t len)2077  void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2078  				 size_t len)
2079  {
2080  	if (audit_string_contains_control(string, len))
2081  		audit_log_n_hex(ab, string, len);
2082  	else
2083  		audit_log_n_string(ab, string, len);
2084  }
2085  
2086  /**
2087   * audit_log_untrustedstring - log a string that may contain random characters
2088   * @ab: audit_buffer
2089   * @string: string to be logged
2090   *
2091   * Same as audit_log_n_untrustedstring(), except that strlen is used to
2092   * determine string length.
2093   */
audit_log_untrustedstring(struct audit_buffer * ab,const char * string)2094  void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2095  {
2096  	audit_log_n_untrustedstring(ab, string, strlen(string));
2097  }
2098  
2099  /* This is a helper-function to print the escaped d_path */
audit_log_d_path(struct audit_buffer * ab,const char * prefix,const struct path * path)2100  void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2101  		      const struct path *path)
2102  {
2103  	char *p, *pathname;
2104  
2105  	if (prefix)
2106  		audit_log_format(ab, "%s", prefix);
2107  
2108  	/* We will allow 11 spaces for ' (deleted)' to be appended */
2109  	pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2110  	if (!pathname) {
2111  		audit_log_format(ab, "\"<no_memory>\"");
2112  		return;
2113  	}
2114  	p = d_path(path, pathname, PATH_MAX+11);
2115  	if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2116  		/* FIXME: can we save some information here? */
2117  		audit_log_format(ab, "\"<too_long>\"");
2118  	} else
2119  		audit_log_untrustedstring(ab, p);
2120  	kfree(pathname);
2121  }
2122  
audit_log_session_info(struct audit_buffer * ab)2123  void audit_log_session_info(struct audit_buffer *ab)
2124  {
2125  	unsigned int sessionid = audit_get_sessionid(current);
2126  	uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2127  
2128  	audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2129  }
2130  
audit_log_key(struct audit_buffer * ab,char * key)2131  void audit_log_key(struct audit_buffer *ab, char *key)
2132  {
2133  	audit_log_format(ab, " key=");
2134  	if (key)
2135  		audit_log_untrustedstring(ab, key);
2136  	else
2137  		audit_log_format(ab, "(null)");
2138  }
2139  
audit_log_task_context(struct audit_buffer * ab)2140  int audit_log_task_context(struct audit_buffer *ab)
2141  {
2142  	char *ctx = NULL;
2143  	unsigned len;
2144  	int error;
2145  	u32 sid;
2146  
2147  	security_task_getsecid(current, &sid);
2148  	if (!sid)
2149  		return 0;
2150  
2151  	error = security_secid_to_secctx(sid, &ctx, &len);
2152  	if (error) {
2153  		if (error != -EINVAL)
2154  			goto error_path;
2155  		return 0;
2156  	}
2157  
2158  	audit_log_format(ab, " subj=%s", ctx);
2159  	security_release_secctx(ctx, len);
2160  	return 0;
2161  
2162  error_path:
2163  	audit_panic("error in audit_log_task_context");
2164  	return error;
2165  }
2166  EXPORT_SYMBOL(audit_log_task_context);
2167  
audit_log_d_path_exe(struct audit_buffer * ab,struct mm_struct * mm)2168  void audit_log_d_path_exe(struct audit_buffer *ab,
2169  			  struct mm_struct *mm)
2170  {
2171  	struct file *exe_file;
2172  
2173  	if (!mm)
2174  		goto out_null;
2175  
2176  	exe_file = get_mm_exe_file(mm);
2177  	if (!exe_file)
2178  		goto out_null;
2179  
2180  	audit_log_d_path(ab, " exe=", &exe_file->f_path);
2181  	fput(exe_file);
2182  	return;
2183  out_null:
2184  	audit_log_format(ab, " exe=(null)");
2185  }
2186  
audit_get_tty(void)2187  struct tty_struct *audit_get_tty(void)
2188  {
2189  	struct tty_struct *tty = NULL;
2190  	unsigned long flags;
2191  
2192  	spin_lock_irqsave(&current->sighand->siglock, flags);
2193  	if (current->signal)
2194  		tty = tty_kref_get(current->signal->tty);
2195  	spin_unlock_irqrestore(&current->sighand->siglock, flags);
2196  	return tty;
2197  }
2198  
audit_put_tty(struct tty_struct * tty)2199  void audit_put_tty(struct tty_struct *tty)
2200  {
2201  	tty_kref_put(tty);
2202  }
2203  
audit_log_task_info(struct audit_buffer * ab)2204  void audit_log_task_info(struct audit_buffer *ab)
2205  {
2206  	const struct cred *cred;
2207  	char comm[sizeof(current->comm)];
2208  	struct tty_struct *tty;
2209  
2210  	if (!ab)
2211  		return;
2212  
2213  	cred = current_cred();
2214  	tty = audit_get_tty();
2215  	audit_log_format(ab,
2216  			 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2217  			 " euid=%u suid=%u fsuid=%u"
2218  			 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2219  			 task_ppid_nr(current),
2220  			 task_tgid_nr(current),
2221  			 from_kuid(&init_user_ns, audit_get_loginuid(current)),
2222  			 from_kuid(&init_user_ns, cred->uid),
2223  			 from_kgid(&init_user_ns, cred->gid),
2224  			 from_kuid(&init_user_ns, cred->euid),
2225  			 from_kuid(&init_user_ns, cred->suid),
2226  			 from_kuid(&init_user_ns, cred->fsuid),
2227  			 from_kgid(&init_user_ns, cred->egid),
2228  			 from_kgid(&init_user_ns, cred->sgid),
2229  			 from_kgid(&init_user_ns, cred->fsgid),
2230  			 tty ? tty_name(tty) : "(none)",
2231  			 audit_get_sessionid(current));
2232  	audit_put_tty(tty);
2233  	audit_log_format(ab, " comm=");
2234  	audit_log_untrustedstring(ab, get_task_comm(comm, current));
2235  	audit_log_d_path_exe(ab, current->mm);
2236  	audit_log_task_context(ab);
2237  }
2238  EXPORT_SYMBOL(audit_log_task_info);
2239  
2240  /**
2241   * audit_log_path_denied - report a path restriction denial
2242   * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2243   * @operation: specific operation name
2244   */
audit_log_path_denied(int type,const char * operation)2245  void audit_log_path_denied(int type, const char *operation)
2246  {
2247  	struct audit_buffer *ab;
2248  
2249  	if (!audit_enabled || audit_dummy_context())
2250  		return;
2251  
2252  	/* Generate log with subject, operation, outcome. */
2253  	ab = audit_log_start(audit_context(), GFP_KERNEL, type);
2254  	if (!ab)
2255  		return;
2256  	audit_log_format(ab, "op=%s", operation);
2257  	audit_log_task_info(ab);
2258  	audit_log_format(ab, " res=0");
2259  	audit_log_end(ab);
2260  }
2261  
2262  /* global counter which is incremented every time something logs in */
2263  static atomic_t session_id = ATOMIC_INIT(0);
2264  
audit_set_loginuid_perm(kuid_t loginuid)2265  static int audit_set_loginuid_perm(kuid_t loginuid)
2266  {
2267  	/* if we are unset, we don't need privs */
2268  	if (!audit_loginuid_set(current))
2269  		return 0;
2270  	/* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2271  	if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2272  		return -EPERM;
2273  	/* it is set, you need permission */
2274  	if (!capable(CAP_AUDIT_CONTROL))
2275  		return -EPERM;
2276  	/* reject if this is not an unset and we don't allow that */
2277  	if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2278  				 && uid_valid(loginuid))
2279  		return -EPERM;
2280  	return 0;
2281  }
2282  
audit_log_set_loginuid(kuid_t koldloginuid,kuid_t kloginuid,unsigned int oldsessionid,unsigned int sessionid,int rc)2283  static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2284  				   unsigned int oldsessionid,
2285  				   unsigned int sessionid, int rc)
2286  {
2287  	struct audit_buffer *ab;
2288  	uid_t uid, oldloginuid, loginuid;
2289  	struct tty_struct *tty;
2290  
2291  	if (!audit_enabled)
2292  		return;
2293  
2294  	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2295  	if (!ab)
2296  		return;
2297  
2298  	uid = from_kuid(&init_user_ns, task_uid(current));
2299  	oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2300  	loginuid = from_kuid(&init_user_ns, kloginuid),
2301  	tty = audit_get_tty();
2302  
2303  	audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2304  	audit_log_task_context(ab);
2305  	audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2306  			 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2307  			 oldsessionid, sessionid, !rc);
2308  	audit_put_tty(tty);
2309  	audit_log_end(ab);
2310  }
2311  
2312  /**
2313   * audit_set_loginuid - set current task's loginuid
2314   * @loginuid: loginuid value
2315   *
2316   * Returns 0.
2317   *
2318   * Called (set) from fs/proc/base.c::proc_loginuid_write().
2319   */
audit_set_loginuid(kuid_t loginuid)2320  int audit_set_loginuid(kuid_t loginuid)
2321  {
2322  	unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2323  	kuid_t oldloginuid;
2324  	int rc;
2325  
2326  	oldloginuid = audit_get_loginuid(current);
2327  	oldsessionid = audit_get_sessionid(current);
2328  
2329  	rc = audit_set_loginuid_perm(loginuid);
2330  	if (rc)
2331  		goto out;
2332  
2333  	/* are we setting or clearing? */
2334  	if (uid_valid(loginuid)) {
2335  		sessionid = (unsigned int)atomic_inc_return(&session_id);
2336  		if (unlikely(sessionid == AUDIT_SID_UNSET))
2337  			sessionid = (unsigned int)atomic_inc_return(&session_id);
2338  	}
2339  
2340  	current->sessionid = sessionid;
2341  	current->loginuid = loginuid;
2342  out:
2343  	audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2344  	return rc;
2345  }
2346  
2347  /**
2348   * audit_signal_info - record signal info for shutting down audit subsystem
2349   * @sig: signal value
2350   * @t: task being signaled
2351   *
2352   * If the audit subsystem is being terminated, record the task (pid)
2353   * and uid that is doing that.
2354   */
audit_signal_info(int sig,struct task_struct * t)2355  int audit_signal_info(int sig, struct task_struct *t)
2356  {
2357  	kuid_t uid = current_uid(), auid;
2358  
2359  	if (auditd_test_task(t) &&
2360  	    (sig == SIGTERM || sig == SIGHUP ||
2361  	     sig == SIGUSR1 || sig == SIGUSR2)) {
2362  		audit_sig_pid = task_tgid_nr(current);
2363  		auid = audit_get_loginuid(current);
2364  		if (uid_valid(auid))
2365  			audit_sig_uid = auid;
2366  		else
2367  			audit_sig_uid = uid;
2368  		security_task_getsecid(current, &audit_sig_sid);
2369  	}
2370  
2371  	return audit_signal_info_syscall(t);
2372  }
2373  
2374  /**
2375   * audit_log_end - end one audit record
2376   * @ab: the audit_buffer
2377   *
2378   * We can not do a netlink send inside an irq context because it blocks (last
2379   * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2380   * queue and a tasklet is scheduled to remove them from the queue outside the
2381   * irq context.  May be called in any context.
2382   */
audit_log_end(struct audit_buffer * ab)2383  void audit_log_end(struct audit_buffer *ab)
2384  {
2385  	struct sk_buff *skb;
2386  	struct nlmsghdr *nlh;
2387  
2388  	if (!ab)
2389  		return;
2390  
2391  	if (audit_rate_check()) {
2392  		skb = ab->skb;
2393  		ab->skb = NULL;
2394  
2395  		/* setup the netlink header, see the comments in
2396  		 * kauditd_send_multicast_skb() for length quirks */
2397  		nlh = nlmsg_hdr(skb);
2398  		nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2399  
2400  		/* queue the netlink packet and poke the kauditd thread */
2401  		skb_queue_tail(&audit_queue, skb);
2402  		wake_up_interruptible(&kauditd_wait);
2403  	} else
2404  		audit_log_lost("rate limit exceeded");
2405  
2406  	audit_buffer_free(ab);
2407  }
2408  
2409  /**
2410   * audit_log - Log an audit record
2411   * @ctx: audit context
2412   * @gfp_mask: type of allocation
2413   * @type: audit message type
2414   * @fmt: format string to use
2415   * @...: variable parameters matching the format string
2416   *
2417   * This is a convenience function that calls audit_log_start,
2418   * audit_log_vformat, and audit_log_end.  It may be called
2419   * in any context.
2420   */
audit_log(struct audit_context * ctx,gfp_t gfp_mask,int type,const char * fmt,...)2421  void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2422  	       const char *fmt, ...)
2423  {
2424  	struct audit_buffer *ab;
2425  	va_list args;
2426  
2427  	ab = audit_log_start(ctx, gfp_mask, type);
2428  	if (ab) {
2429  		va_start(args, fmt);
2430  		audit_log_vformat(ab, fmt, args);
2431  		va_end(args);
2432  		audit_log_end(ab);
2433  	}
2434  }
2435  
2436  EXPORT_SYMBOL(audit_log_start);
2437  EXPORT_SYMBOL(audit_log_end);
2438  EXPORT_SYMBOL(audit_log_format);
2439  EXPORT_SYMBOL(audit_log);
2440